1. Field of the Invention
This invention relates generally to beverage brewers, and is concerned in particular with an improved system for puncturing and venting single serve beverage filter cartridges utilized in the brew cycles of such brewers.
2. Description of the Prior Art
It is known, as disclosed for example in U.S. Pat. Nos. 5,325,765 (Sylvan et al.) and U.S. Pat. Nos. 5,840,189 (Sylvan et al.) to employ sharpened tubular inlet and outlet probes to puncture the lid and base of a single serve beverage filter cartridge. The inlet probe admits heated liquid into the cartridge for combination with a beverage medium to produce a beverage which then exits the cartridge via the outlet probe. While this arrangement operates in a generally satisfactory manner, experience has indicated that the cartridge interiors occasionally become pressurized as a result of altitude or temperature changes and/or outgassing of the beverage medium. If internal pressures are relieved by venting through the inlet probe, particles of the beverage medium may be entrained with the exiting gas, causing clogging of the inlet probe and a malfunction of the brewer.
The objective of the present invention is to avoid or at least significantly minimize this problem by first puncturing the cartridge with the outlet probe, followed sequentially with a second puncturing by the inlet probe. In this manner, the cartridge is initially vented through the outlet probe, which then will be flushed clean by the exiting beverage flow.